The laboratory demonstrator, assisting technician and students are responsible for ensuring a number of practices are followed.
Damaged sources may present a contamination hazard that could be expensive to clean up or could present a health hazard if internal contamination occurs. If a source is damaged the School Radiation Safety Officer or the Radiation Safety Officer must be contacted immediately. The area around the source must be isolated to prevent spread of contamination by movement of equipment or people.
Sources should be handled with tweezers. Maintaining a distance of 10cm from the source can reduce the radiation dose to your fingers by as much as 10,000 times.
Shielding should be provided where the source is in close proximity (less than 50cm) to students for extended periods of time (over an hour), and it should be lead. No special shielding is required if the activity limits of schools' sources (listed below) are not reached.
Time near radioactive sources should be kept to a minimum, for example holding a radioactive source in your fingers for an extended period is very poor practice.
Activity of sources used should be kept to a practical minimum.
241Am emits alpha particles and is bonded to an open metal surface in a shallow well of the source disk. Do not touch or physically damage this surface as 241Am Contamination may result.
Recommended activity limits for school sources are:
57Co Mossbauer sources can have very high activities. These sources should only be used with second- and third-year students. The radiation hazards must be carefully explained in the laboratory notes and verbally by the supervisor before starting the experiment.
Under no circumstances should the source be handled with fingers. The source must be shielded where ever possible; 5mm lead is generally sufficient. The 57Co is plated on the surface of the source and physical contact with this surface is to be avoided at all times.
Reference: This material was taken from the NHMRC Code of Practice for the Safe Use of Ionizing Radiation in Secondary Schools (1986); responsibility for this document now rests with the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).